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Re: Subtitle/caption styling + TTML + CSS

From: Pierre-Anthony Lemieux <pal@sandflow.com>
Date: Mon, 12 Dec 2016 17:43:20 -0800
Message-ID: <CAF_7JxB7dd=o3nOBO95CD+U+aYMbc-o9_nwo0GYN3=PS3vD-1A@mail.gmail.com>
To: Glenn Adams <glenn@skynav.com>
Cc: "public-tt@w3.org" <public-tt@w3.org>
> have you tried a combination of {min,max}-width on the span

No. How would it work?

> you probably should include references to these examples in your message to CSS; let's see what input they might have

Ok.

On Mon, Dec 12, 2016 at 5:26 PM, Glenn Adams <glenn@skynav.com> wrote:
>
>
> On Mon, Dec 12, 2016 at 6:11 PM, Pierre-Anthony Lemieux <pal@sandflow.com>
> wrote:
>>
>> Hi Glenn,
>>
>> > since both of the examples you give, multiRowAlign and linePadding
>> >are in fact supported (semantically) by CSS.
>>
>> I am not so sure.
>>
>> >display: inline-block on span to obtain multiRowAlign semantics
>>
>> I have not found a way to make this work without explicit <br>
>> elements -- see [1].
>>
>> [1] https://codepen.io/palemieux/pen/yVxZWm
>
>
> have you tried a combination of {min,max}-width on the span
>
>>
>>
>>
>> >use box-decoration-break: clone to obtain linePadding semantics.
>>
>> I have not found a way to make this work if nested spans are used --
>> see [2] for HTML and attached for TTML. Specifically, linePadding
>> requires that the background of the first/last character of each line
>> be extended.
>>
>> - "box-decoration-break: clone" extends the background of the <span>
>> at the end of each line, so the background of both outer and inner
>> spans are extended.
>>
>> - CSS padding adds padding to both left and right of a span,
>> introducing additional spaces in the text
>>
>> [2] https://codepen.io/palemieux/pen/vyzbqW
>>
>> Perhaps you see another way. I would love to be proven wrong!
>
>
> hmm, you may have a counterexample here
>
> you probably should include references to these examples in your message to
> CSS; let's see what input they might have
>
>>
>>
>> Best,
>>
>> -- Pierre
>>
>> On Mon, Dec 12, 2016 at 4:12 PM, Glenn Adams <glenn@skynav.com> wrote:
>> > You are likely to receive pushback on your email, since both of the
>> > examples
>> > you give, multiRowAlign and linePadding, are in fact supported
>> > (semantically) by CSS.
>> >
>> > Use display: inline-block on span to obtain multiRowAlign semantics and
>> > use
>> > box-decoration-break: clone to obtain linePadding semantics.
>> >
>> > As far as I know, none of TTML1 or IMSC1 presentation semantics is not
>> > supported by some CSS mapping (whether simple or complex), but that
>> > doesn't
>> > hold for TTML2, where there are indeed some semantic gaps in CSS.
>> >
>> > On Mon, Dec 12, 2016 at 3:21 PM, Pierre-Anthony Lemieux
>> > <pal@sandflow.com>
>> > wrote:
>> >>
>> >> FYI. My input to the www-style list re: TTML and CSS.
>> >>
>> >> Best,
>> >>
>> >> -- Pierre
>> >>
>> >>
>> >> ---------- Forwarded message ----------
>> >> From: Pierre-Anthony Lemieux <pal@sandflow.com>
>> >> Date: Sun, Dec 11, 2016 at 9:04 PM
>> >> Subject: Subtitle/caption styling + TTML + CSS
>> >> To: "L. David Baron" <dbaron@dbaron.org>
>> >> Cc: Thierry MICHEL <tmichel@w3.org>, Bert Bos <bert@w3.org>, Chris
>> >> Lilley <chris@w3.org>, www-style list <www-style@w3.org>, Nigel Megitt
>> >> <nigel.megitt@bbc.co.uk>
>> >>
>> >>
>> >> Hi David et al.,
>> >>
>> >> > I don't think TTML1 was designed in a
>> >> > way that would fit well in browser implementations.
>> >>
>> >> I have been working on an open source JavaScript library [1] for
>> >> rendering TTML1 documents to HTML5 fragments.
>> >>
>> >> [1] https://github.com/sandflow/imscJS
>> >>
>> >> TTML is based on XSL, which is based on CSS, and so the mapping has
>> >> been straightforward. [ed.: I am not sure what you mean by "does not
>> >> fit well", perhaps you can elaborate.]
>> >>
>> >> The most significant challenge has been supporting two features
>> >> (linePadding and multiRowAlign [2]), which are not supported in CSS,
>> >> but have been identified as essential to captioning in Europe by the
>> >> TTWG (and EBU).
>> >>
>> >> [2] https://www.w3.org/TR/ttml-imsc1/#linepadding
>> >>
>> >> I would think that features that are important to
>> >> subtitling/captioning should be considered for CSS, regardless of the
>> >> ultimate timed text format (TTML, WebVTT, etc...)
>> >>
>> >> Best,
>> >>
>> >> -- Pierre
>> >>
>> >> On Wed, Nov 23, 2016 at 3:33 PM, L. David Baron <dbaron@dbaron.org>
>> >> wrote:
>> >> > On Friday 2016-11-18 17:48 +0100, Thierry MICHEL wrote:
>> >> >> CSS colleagues,
>> >> >>
>> >> >> The Timed Text Working Group (TTWG) published yesterday an ordinary
>> >> >> Working
>> >> >> Draft of Timed Text Markup Language 2 (TTML2)
>> >> >> W3C Working Draft 17 November 2016
>> >> >> https://www.w3.org/TR/2016/WD-ttml2-20161117/
>> >> >>
>> >> >> FYI, this publication is not the last publication before requesting
>> >> >> transition to Candidate Recommendation. The TTWG plans to publish a
>> >> >> final WD
>> >> >> soon. We will let you know.
>> >> >>
>> >> >> Meanwhile, the TTWG invites you to review this TTML2 WD.
>> >> >>
>> >> >> The horizontal review should focus only on the new features
>> >> >> introduced in TTML2.
>> >> >> Please refer to the section for changes between Timed Text Markup
>> >> >> Language
>> >> >> (TTML) Version 1 (TTML1) and Version 2 (TTML2).
>> >> >>
>> >> >>
>> >> >> https://www.w3.org/TR/2016/WD-ttml2-20161117/#changes-from-ttml1-vocabulary
>> >> >>
>> >> >> Please send your comments to  TTWG Public mailing list
>> >> >> <public-tt@w3.org>.
>> >> >
>> >> > So it's worth noting that the styling section of the draft:
>> >> >   https://w3c.github.io/ttml2/spec/ttml2.html#styling
>> >> > has considerable new additions relative to TTML1.  This section
>> >> > contains a vocabulary that is rather similar to many CSS properties,
>> >> > but also contains significant divergence.
>> >> >
>> >> > In particular, TTML1 had in
>> >> > https://www.w3.org/TR/ttaf1-dfxp/#styling-attribute-vocabulary
>> >> > the following styling attributes that appear to match CSS at first
>> >> > glance, at least in semantics:
>> >> >   backgroundColor
>> >> >   color
>> >> >   direction
>> >> >   display (only auto vs. none)
>> >> >   extent (a shorthand for width and height)
>> >> >   fontFamily
>> >> >   fontSize
>> >> >   fontStyle
>> >> >   fontWeight
>> >> >   lineHeight
>> >> >   opacity
>> >> >   overflow
>> >> >   padding
>> >> >   textAlign
>> >> >   textDecoration (but with extra values)
>> >> >   unicodeBidi
>> >> >   visibility
>> >> >   wrapOption (like text-wrap in css-text-4)
>> >> >   writingMode (but using old values)
>> >> >   zIndex
>> >> > and the following styling attributes that do not match CSS:
>> >> >   displayAlign
>> >> >   origin (a bit like x and y in SVG)
>> >> >   showBackground
>> >> >   textOutline
>> >> >
>> >> > TTML2 introduces the following new properties that appear to have
>> >> > similar CSS properties at first glance:
>> >> >   backgroundClip (with different names for the values)
>> >> >   backgroundExtent (equivalent to background-size)
>> >> >   backgroundImage
>> >> >   backgroundOrigin (with different names for the values)
>> >> >   backgroundPosition
>> >> >   backgroundRepeat
>> >> >   border (with border-radius included in the property)
>> >> >   bpd (equivalent to block-size in css-logical-properties)
>> >> >   fontKerning (though without CSS's initial value, which is auto!)
>> >> >   ipd (equivalent to inline-size in css-logical-properties)
>> >> >   letterSpacing
>> >> >   ruby (this is done using the display property in CSS)
>> >> >   rubyAlign (with additional auto, end, and withBase values)
>> >> >   rubyPosition (with before/after names instead of over/under)
>> >> >   textCombine (equivalent to CSS text-combine-horizontal)
>> >> >   textEmphasis
>> >> >   textOrientation (but retaining the sidewaysLeft and sidewaysRight
>> >> >     values that CSS removed)
>> >> >   textShadow
>> >> > and the following that appear not to have corresponding CSS
>> >> > properties:
>> >> >   disparity
>> >> >   fontSelectionStrategy
>> >> >   fontShear
>> >> >   fontVariant (this is a property name used in CSS, but with a
>> >> >     different meaning!)
>> >> >   position (this is a property name used in CSS, but with a
>> >> >     different value, "center", although one that has been proposed
>> >> >     to be added to the CSS property)
>> >> >   rubyOffset
>> >> >   rubyOverflow
>> >> >   rubyOverhang
>> >> >   rubyOverhangClass
>> >> >   rubyReserve
>> >> >
>> >> >
>> >> > My opinion on this is that this seems like a lot of divergence from
>> >> > CSS.  It's divergence in naming (using different names for the same
>> >> > thing and the same names for different things), divergence in value
>> >> > spaces, and given that everything is redefined in the TTML spec
>> >> > (although often non-normatively "based on" CSS specs), almost
>> >> > certainly massive divergence in semantics.
>> >> >
>> >> > I think TTML and CSS have largely been implemented in separate
>> >> > implementations (which means that TTML has largely not been
>> >> > implemented in browsers), and I don't think TTML1 was designed in a
>> >> > way that would fit well in browser implementations.  That's why
>> >> > browsers implemented WebVTT instead.  I think continuing to diverge
>> >> > from CSS to this degree simply makes TTML implementation in browsers
>> >> > even less likely than it already was (which was already unlikely).
>> >> >
>> >> > On the flip side, I don't think fixing that divergence is
>> >> > particularly valuable (at least to browsers) since the communities
>> >> > are already separate, and I think the chance of getting substantial
>> >> > TTML implementation in browsers is low even without additional
>> >> > divergence.
>> >> >
>> >> > -David
>> >> >
>> >> > --
>> >> > 𝄞   L. David Baron                         http://dbaron.org/   𝄂
>> >> > 𝄢   Mozilla                          https://www.mozilla.org/   𝄂
>> >> >              Before I built a wall I'd ask to know
>> >> >              What I was walling in or walling out,
>> >> >              And to whom I was like to give offense.
>> >> >                - Robert Frost, Mending Wall (1914)
>> >>
>> >
>
>
Received on Tuesday, 13 December 2016 01:44:15 UTC

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